It was originally scheduled to be released last Friday, but got delayed due to last-minute quality assurance check. Nonetheless, the second beta of Firefox 4.0 is now here. It is available for Windows, Mac OS X and Linux, although the features are not uniform throughout (more on that later).

Firefox 4.0 Beta 2 has some new features like - better handling of retained layers on page, CSS 3 transitions etc. There is a new add-ons manager and extensions API as well. Another new feature that has made it to this release is the "App Tab" - similar to the "Pin Tab" feature in Chrome. The JavaScript engine has also been optimized to make it faster. (We will be testing that later.)

There are also visual change for the Mac OS X version. It joins the Windows version in having the new "Tabs on Top" interface. Sadly the Linux version is yet to get this new user interface.

Firefox 4.0 Beta 2 feels much faster and smoother than the first beta. So, if you are using Beta 1 consider upgrading. Otherwise, it is the same old warning - "This is not a stable release and you may experience problems". Download link below: